Miscellaneous active electrical nonlinear devices – circuits – and – Specific signal discriminating without subsequent control – By amplitude
Reexamination Certificate
1999-09-28
2002-09-17
Le, Dinh T. (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Specific signal discriminating without subsequent control
By amplitude
C327S554000, C330S009000
Reexamination Certificate
active
06452424
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to active analog signal processing circuits. More particularly, the present invention relates to an active analog signal processing circuit that processes signals associated with multiple channels.
BACKGROUND OF THE INVENTION
Multiple channel signal processing circuits are common in such applications as cellular telephone systems, stereo audio systems, and home theater systems. For example, the analog front end portion of a cellular telephone system may utilize well known quadrature modulation techniques to process in-phase and quadrature-phase baseband signals associated with different channels (I/Q signals). Conventional multiple channel systems have employed duplicate analog circuits for each signal channel. Such analog circuits typically include a plurality of active circuit components and any number of passive electronic components.
FIG. 1
is a general block diagram representation of a prior art multiple channel processing circuit
100
configured to accommodate an in-phase (“I”) input signal
102
and a quadrature (“Q”) input signal
104
. For purposes of this general introduction, the specific function of circuit
100
need not be described in detail; circuit
100
may be utilized in any number of applications such as a switched-capacitor filter, an analog to digital converter, a switched-capacitor digital to analog converter, or the like. In the present context, circuit
100
utilizes discrete time sampling of analog input signals. I-input signal
102
and Q-input signal
104
are each sampled in accordance with a given sampling rate and sampling period. An analog processing circuit
106
associated with the I-input signal
102
includes a number of active circuit components
108
and a number of passive circuit components
1
10
. Similarly, an analog processing circuit
112
associated with the Q-input signal
104
includes a number of active circuit components
114
and a number of passive circuit components
116
. Analog processing circuit
106
and analog processing circuit
112
may be substantially identical to one another. In this manner, prior art techniques simply duplicate the analog processing circuits N times to accommodate N signal processing channels.
Analog processing circuit
106
produces an I-output signal
118
, while analog processing circuit
112
produces a Q-output signal
120
. Output signals
118
and
120
are generated in a sampled manner in response to the particular characteristics of analog processing circuits
106
and
112
. Output signals
118
and
120
may be further processed in accordance with any number of conventional techniques depending upon the specific application.
Although the prior art approach may simplify the design aspect of a multiple channel system, it has some practical limitations. For example, as the number of channels increase, the required prior art circuitry will proportionately increase, with a corresponding increase in power consumption and semiconductor die size. However, with the increasing demand for hardware miniaturization, the amount of power, physical size, and number of components associated with semiconductor implementations can place limitations on the design of the analog circuitry. Accordingly, due to practical size and power constraints, the simple duplication of active signal processing circuits may not be a desirable implementation for a multiple channel signal processing application.
SUMMARY OF THE INVENTION
A multiple channel signal processing solution in accordance with the present invention utilizes a shared active circuit component to process a plurality of input signals during a sampling period. Rather than merely duplicating an active processing circuit for each input channel, the exemplary system employs at least one common active electronic component in conjunction with similar passive component networks associated with each channel. The reduction of active circuit components results in a reduction of operating power and a reduction in the size of the semiconductor implementation. Thus, a practical embodiment may be realized in a compact manner and without a considerable increase in the power requirements.
The above and other features of the present invention may be carried out in one form by a multiple channel signal processing circuit having a first input associated with a first signal for a first channel, a second input associated with a second signal for a second channel, a network of passive electronic components configured to process samples of the first signal and samples of the second signal, a shared active electronic component configured to process samples of the first signal and samples of the second signal, and a channel switching mechanism configured to switch between processing states associated with the first channel and the second channel during a sampling period.
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Cops Wim
Shamlou Daryush
Xiang Yihai
Yin Guang-Ming
Zhang Bo
Conexant Systems Inc.
Farjami & Farjami LLP
Le Dinh T.
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